This research will explore the organization, structure and expression of human ferritin genes. Cloned cDNA for H and L chains will be used to characterize the H and L gene families and to identify genes coding for the H and L subunits of tissue and serum ferritins. Their chromosomal location will be determined by in situ hybridization to chromosome spreads and by hybridization to DNA from separated chromosomes. Expressed genes will be identified from Southern analysis of DNA from rodent/human hybrid cell lines that express human H or L chains and by use of specific subprobes from cDNA clones and the 5' end of ferritin mRNAs. Genomic clones containing H and L genes will be isolated from genomic libraries. The organization and structure of expressed genes will be determined by use of restriction mapping and hybridization of the genomic clones to appropriate sub-probes, R loop and heteroduplex mapping, and finally by sequencing. Genes exhibiting conditional or tissue-specific differential expression will be identified and elements involved in possible regulation of their expression will be analyzed. Exon-intro junctions will be identified as well as possible regulatory sequences at the 5' end of the genes that may be involved in initiation or regulation of transcription or processing of tissue specific ferritins. These studies will eventually lead to an analysis of factors that might control the regulation of expression of H and L chains in different tissues and at different developmental stages. We shall investigate the possibility that defects in iron metabolism such as hemochromatosis or neonatal iron storage disease are causally related to abnormalities in ferritin expression. In related collaborative studies we shall explore the use of ferritin probes to determine whether any will be useful markers for identifying restriction fragment length polymorphisms associated with other inherited diseases where an altered gene lies close to ferritin. In parallel studies, we shall examine the interaction of ferritin mRNA and proteins and ribosomal RNA sequences in messenger ribonucleoprotein particles to explore their function in translational control of ferritin synthesis.